This invention generally relates to intravascular catheters, such as balloon dilatation catheters used in percutaneous transluminal coronary angioplasty (PTCA).
In classic PTCA procedures, a guiding catheter having a preshaped distal tip is percutaneously introduced into the cardiovascular system of a patient and advanced therein until the preshaped distal tip of the guiding catheter is disposed within the aorta adjacent the ostium of the desired coronary artery. The guiding catheter is twisted or torqued from the proximal end to turn the distal tip of the guiding catheter so that it can be guided into the desired coronary ostium. With over-the-wire systems, a guidewire and a balloon dilatation catheter are introduced into and advanced through the guiding catheter to the distal tip thereof, with the guidewire slidably disposed within an inner lumen of the dilatation catheter. The guidewire is first advanced out the distal tip of the guiding catheter, which is seated in the ostium of the patient's coronary artery, until the distal end of the guidewire crosses the lesion to be dilated. The dilatation catheter is then advanced out of the distal tip of the guiding catheter, over the previously advanced guidewire, until the balloon on the distal extremity of the dilatation catheter is properly positioned across the lesion. Once properly positioned, the balloon is inflated to a predetermined size with radiopaque liquid at relatively high pressures (e.g., generally 4-12 atmospheres) to dilate the stenosed region of the diseased artery. One or more inflations may be necessary to effectively dilate the stenosis. Additional stenoses may be dilatated with the same catheter. When the dilatations are completed, the balloon is deflated so that the dilatation catheter can be removed from the dilated stenosis and blood flow will resume through the dilated artery.
Further details of guiding catheters, dilatation catheters, guidewires, and other devices for angioplasty procedures can be found in U.S. Pat. No. 4,323,071 (Simpson-Robert); U.S. Pat. No. 4,439,185 (Lundquist); U.S. Pat. No. 4,468,224 (Enzmann et al.); U.S. Pat. No. 4,516,972 (Samson); U.S. Pat. No. 4,538,622 (Samson et al.); U.S. Pat. No. 4,554,929 (Samson et al.); U.S. Pat. No. 4,582,181 (Samson); U.S. Pat. No. 4,616,625 (Simpson); U.S. Pat. No. 4,638,805 (Powell); U.S. Pat. No. 4,478,986 (Morrison et al.); U.S. Pat. No. 4,898,577 (Badger et al.); and U.S. Pat. No. 4,827,941 (Taylor et al.) which are hereby incorporated herein in their entirety by reference thereto.
Fixed-wire dilatation catheters for coronary angioplasty, which were first described in U.S. Pat. No. 4,252,181 (Samson), now U.S. Pat. No. Re. 33,166, are similarly used except there is no longitudinal movement between the guidewire and the catheter. The fixed-wire dilatation catheters generally have an outer tubular member with an inflatable balloon on the distal section thereof which is capable of dilating a stenosis, and a guiding member extending out through the distal end of the balloon which aids in advancing the catheter to a desired location within the patient's vasculature. They usually have no inner tubular member and therefore have lower profiles, e.g., transverse dimensions, than over-the-wire dilatation catheters having the same inflated balloon size. Moreover, because the fixed-wire catheters have the guidewire or guiding member fixed or at least restricted as to longitudinal movement, these catheters generally have greater pushability than over-the-wire type catheters such as described and claimed in U.S. Pat. No. 4,323,071 (Simpson-Robert). The lower profile and greater pushability of the fixed-wire dilatation catheters allows them to cross tighter lesions and to be advanced much deeper into a patient's coronary anatomy than the over-the-wire dilatation catheters of comparable sizes.
The assignee of the present invention, Advanced Cardiovascular Systems, Inc., markets an improved dilatation catheter under the trademark ACS RX (R) which is described and claimed in U.S. Pat. No. 5,040,548 (Yock), U.S. Pat. No. 5,061,273 (Yock) and U.S. Pat. No. 4,748,982 (Horzewski et al.). This dilatation catheter has a short guidewire receiving sleeve or inner lumen extending through a distal portion of the catheter. The sleeve or inner lumen extends proximally a distance of at least about 10 cm and usually not more than about 50 cm from a first guidewire port in the distal end of the catheter to a second guidewire port in the catheter spaced proximally from the inflatable member of the catheter. Preferably, a slit is provided in the wall of the catheter body which extends distally from the second guidewire port, preferably to a location proximal to the proximal end of the inflatable balloon. The structure of the catheter allows for the rapid exchange of the catheter without the need for an exchange wire or adding a guidewire extension to the proximal end of the guidewire. The design of this catheter has been widely praised by the medical profession and has been met with much success in the market place because of the advantages of its unique design.
A major and continual thrust of development work in the field of intravascular catheters, particularly coronary angioplasty catheters, has been to reduce the profile, i.e., transverse dimensions, of such catheters and to improve the flexibility thereof without detrimentally affecting the pushability, particularly in the distal portion of such catheters. A reduction in profile with little or no loss in pushability allow a dilatation catheter to be advanced much further into a patient's coronary vasculature and to cross much tighter lesions. Fixed-wire dilatation catheters have provided lower profiles and increased pushability, but their use in coronary angioplasty has recently been somewhat limited due to the fact that if the fixed-wire catheter must be removed from an arterial location, access to that location is usually lost. One of the advantages of the over-the-wire dilatation catheter systems over the fixed-wire systems is that the over-the-wire systems allow the guidewire to be left in place while the dilatation catheter is removed and replaced so as to not loose the arterial location.
What has been needed and heretofore unavailable is a low profile dilatation catheter which allows for catheter exchange without loss of arterial position, particularly such a catheter with a single inner lumen. The present invention satisfies this and other needs.